A vehicle seat comprising a seat back frame made of a pipe member shaped like a rectangular frame, a reinforcing member fixed in a position tilted from an upper portion of a laterally outer side of the frame to a lower portion of a laterally inner side of the frame has hitherto been known in the art (see JP 11-222088 A). The reinforcing member has outer ends protruding from the frame, and end portions provided with flanges.
In this vehicle seat, a side collision load imposed on one flange from a laterally outer side is transmitted through the reinforcing member and the other flange to a side laterally opposite to a side on which the one flange is provided.
With the conventional technique as mentioned above, the load can be received at a large area by the flange provided on the reinforcing member, but depending on the direction from which the load is received, the flange would possibly become deformed by the load; therefore, there is a risk of becoming unable to transmit the load satisfactorily.
Against this backdrop, the inventors named in the present application have created the present invention in the process of research for providing a vehicle seat in which the transmission of the load can be achieved satisfactorily.